Dogpile consists of two subsystems, one building on top of the other.

dogpile provides the concept of a "dogpile lock", a control structure
which allows a single thread of execution to be selected as the
"creator" of some resource, while allowing other threads of execution to
refer to the previous version of this resource as the creation proceeds;
if there is no previous version, then those threads block until the
object is available.

dogpile.cache is a caching API which provides a generic interface to
caching backends of any variety, and additionally provides API hooks
which integrate these cache backends with the locking mechanism of
dogpile.

Overall, dogpile.cache is intended as a replacement to the Beaker
caching system, the internals of which are written by the same author.
All the ideas of Beaker which "work" are re- implemented in
dogpile.cache in a more efficient and succinct manner, and all the cruft
(Beaker's internals were first written in 2005) relegated to the trash
heap.